I hope Ashley can give a better answer.
It's just that we're on our own until he comes back after the weekend!
Sorry if my suggestions seem silly, but seeing as this error doesn't trigger on my machine it must be PC-specific, right?
Tho of course, it might as well be a bug. Only Ashley knows how the Node-Webkit preview launcher works.
If I were you I'd try to pinpoint the issue - Make the Construct folder read only, see if any files are disappearing after the error appears by checking the number of files in the folder, etc.